Original-illuminating device for use in an image-reading device

Abstract

A subject or original illuminating device includes a spot-like light source for emitting illuminating light, a plurality of optical fibers having first ends bundled together near the light source and opposite ends arranged in an array along a main scanning line on a subject to be illuminated, the opposite ends in the array being spaced at intervals which are progressively smaller from a center toward opposite ends of the array, and a cylindrical lens disposed between the opposite ends of the optical fibers and the subject for converging the illuminating light from the opposite ends of the optical fibers onto the main scanning line on the subject. The optical fibers may have their opposite ends equally spaced in the array and including selected light emitting ends spaced at intervals which are progressively smaller from a center toward opposite ends of the array, and the cylindrical lens may converge the illuminating light from the selected light emitting ends of the optical fibers onto the main scanning line on the subject.

What is claimed is: 
     
       1. A subject illuminating device comprising: a spot-like light source for emitting illuminating light;   a plurality of optical fibers having first ends bundled together near said light source and opposite ends arranged in an array along a main scanning line on a subject to be illuminated, said opposite ends in the array being spaced at intervals which are progressively smaller from a center toward opposite ends of said array; and   a cylindrical lens disposed between said opposite ends of the optical fibers and said subject for converging, without focusing, the illuminating light from said opposite ends of the optical fibers into a linear beam along the main scanning line on the subject, the distance between the main scanning line and the longitudinal axis of said cylindrical lens being slightly smaller than the focal length of said cylindrical lens with respect to paraxial rays thereof, so that the illuminating light illuminates the main scanning line with greater illuminance at the opposite ends than at the center thereof, and also without small illuminance irregularities.   
     
     
       2. A subject illuminating device according to claim 1, further comprising a cylindrical light guide disposed between said light source and said first ends of the optical fibers and having an inner reflecting wall surface. 
     
     
       3. A subject illuminating device according to claim 1, further comprising a housing which accommodates therein said opposite ends of the optical fibers. 
     
     
       4. A subject illuminating device according to claim 1, wherein some of said intervals are equal to each other. 
     
     
       5. Subject illuminating device according to claim 1, wherein said array is a linear array of only a single row of said opposite ends. 
     
     
       6. A subject illuminating device comprising: a spot-like light source for emitting illuminating light;   a plurality of optical fibers having first ends bundled together near said light source and equally spaced opposite ends arranged in an array along a main scanning line on a subject to be illuminated, said opposite ends including selected light emitting ends spaced at intervals which are progressively smaller from a center toward opposite ends of said array; and   a cylindrical lens disposed between said opposite ends of the optical fibers and said subject for converging, without focusing, the illuminating light from said selected light emitting ends of the optical fibers into a linear beam along the main scanning line on the subject, the distance between the main scanning line and the longitudinal axis of said cylindrical lens being slightly smaller than the focal length of said cylindrical lens with respect to paraxial rays thereof, so that the illuminating light illuminates the main scanning line with greater illuminance at the opposite ends than at the center thereof, and also without small illuminance irregularities.   
     
     
       7. A subject illuminating device according to claim 6, further comprising a cylindrical light guide disposed between said light source and said first ends of the optical fibers and having an inner reflecting wall surface. 
     
     
       8. A subject illuminating device according to claim 6, further comprising a housing which accommodates therein said opposite ends of the optical fibers. 
     
     
       9. Subject illuminating device according to claim 6, wherein said array is a linear array of only a single row of said opposite ends. 
     
     
       10. A subject illuminating device comprising: a spot-like light source for emitting illuminating light;   a plurality of optical fibers having first ends bundled together near sid light source and equally spaced opposite ends arranged in an array along a main scanning line on a subject to be illuminated, said opposite ends including selected light emitting ends spaced at intervals which are progressively smaller from a center toward opposite ends of said array;   a cylindrical lens disposed between said opposite ends of the optical fibers and said subject for converging the illuminating light from said selected light emitting ends of the optical fibers onto the main scanning line on the subject; and   wherein one of said equally spaced opposite ends in the array and said first ends of the optical fibers near said light sources is selectively associated with light-shielding means for making the intervals of said selected light emitting ends progressively smaller from the center toward the opposite ends of said array.   
     
     
       11. A subject illuminating device according to claim 10, wherein said light-shielding means comprises a light-shielding coating on each of selected opposite ends of said optical fibers. 
     
     
       12. A subject illuminating device according to claim 10, wherein some of said intervals are equal to each other. 
     
     
       13. A subject illuminating device comprising: a spot-like light source for emitting illuminating light;   a plurality of optical fibers having first ends bundled together near sid light source and opposite ends arranged in an array along a main scanning line on a subject to be illuminated, said opposite ends in the array being spaced at intervals which are progressively smaller from a center toward opposite ends of said array;   a cylindrical lens disposed between said opposite ends of the optical fibers and said subject for converging the illuminating light from said opposite ends of the optical fibers onto the main scanning line on the subject; and   an image reading device comprising: a charge-coupled device means for photoelectrically converting into an electric image signal the reflected light from said main scanning line; and focusing lens means, disposed between said charge-coupled device and said main scanning line, for focusing said reflected light onto said charge-coupled device means.